Clarifying centrifuge



May 30, 1967 w. LOHSE ETAL CLARIFYING CENTHIFUGE 3 Sheets-Sheet 1 FiledJune 16, 1965 May 30, 1967 w. LOHSE ETAL. 3,322,336

CLARIFYING CENTRIFUGE Filed June 16, 1965 3 Sheets-Sheet 2 y 30, 1967 w.LOHSE ETAL 3,322,336

CLARIFYING CENTRIFUGE Filed June 16, 1965 3 Sheets-Sheet 5 United StatesPatent Ofiiice 3,322,336 Patented May 30, 1967 3,322,336 CLARIFYINGCENTRIFUGE Wilhelm Lohse, Vorberg, Post Ettishofen, Krcis Ravensburg,and Peter Gene, Kressbronn am Bodensee, Germany, assiguors to EscherWyss Aktiengcsellschaft, Zurich, Switzerland, a corporation ofSwitzerland Filed June 16, 1965, Ser. No. 464,315 Claims priority,application Switzerland, June 24, 1964, 8,258/64 9 Claims. (Cl. 233-7)This invention relates to a clarifying centrifuge for separating asuspension into liquid and solid, having a solid-surface drum formingthe external boundary of a separating chamber, on the inner surface ofwhich drum the solid is deposited, while the clarified liquid isdischarged internally.

The known continuously operating clarifying centrifuges are generallyconstructed, in the case of the cylindrical form of the solid-surfacedrum, as scraper-type overflow centrifuges, and in the case of theconical form of the solid-surface drum as worm type centrifuges. In theformer, continuous operation has to be interrupted for a short time,when the drum is filled almost to the overflow edge of the drum withsolid, to scrape the latter out. In the worm type centrifuge, a conicalconveyor worm rotates in the conical solid-surface drum at a differentspeed therefrom for conveying the solid, deposited on the inner surfaceof the drum, to the tapered discharge end of the drum, while thesupernatant liquid is discharged at the wide drum end.

In scraper-type overflow centrifuges, the batch-wise discharge of thesolid is disadvantageous. Under comparable working conditions, however,its clarifying effect is better than that of the worm type centrifuge.It is true that the worm type centrifuge permits extensive drying of thesolid, provided the solid matter content of the feed suspension is nottoo low; owing to the stirring effect of the conveyor worm, however, thedischarge liquid is, as a rule, still relatively turbid and requiresfurther clarification treatment.

It is the object of the invention to provide a clarifying centrifugewhich operates continuously and in addition allows good separation ofliquid and solid to be achieved. In a clarifying centrifuge of thehereinbefore described kind, for this purpose the solid-surface drum isfor-med conically widened and the separating chamber is subdivided inthe axial direction into two or more separating chambers, through whichthe suspension flows successively, subdivision into the chambers beingeffected by partitions extending at least to the vicinity of the wall ofthe solid-surface drum, said partitions having a bottom dischargesituated on their outer edge for the deposited solid, and an overflow,situated closer to the axis of the centrifuge than the bottom discharge,for the suspension or clarified liquid.

Constructional examples of the subject of the invention are shown insimplified form in the drawing.

FIG. 1 shows an axial section through a clarifying centrifuge,

FIG. 1a is a top plan view of the internal parts of a clarifyingcentrifuge similar to that shown in FIG. 1, but employing separatebearing rings connected with each partition,

FIGS. 2 and 3 embodiments,

FIG. 4 shows a portion of an axial section through a particularembodiment of a partition, and

FIG. 5 shows an axial section through a further embodiment.

The clarifying centrifuge shown in FIG. 1 has a rotor comprising aflaring solid-surface drum 1, which is show axial sections throughfurther mounted by means of a shaft 2, secured to its narrow end, in ahousing 3, and forms the outer boundary of a separating chamber 4. Astationary feed pipe 5 is arranged concentric with regard to thesolid-surface drum 1 and extends from the side opposite the shaft 2 intothe solidsurface drum 1 as far as into the vicinity of its narrow end.

The separating chamber 4 of the flaring solid-surface drum 1 issubdivided in the axial direction of the centrifuge by partitions 6 6 6into three separating chambers 4 4 4 The partitions 6 6 6 leave betweentheir outer boundary and the inner surface of the flaring drum 1 anannular gap 7 or 7 7 serving as a bottom discharge for the depositedsolid matter and have an overflow 8 or 8 8 situated closer to the axisof the centrifuge than said bottom discharge. A tubular support 9connects the partitions 6 6 '6 together and by means of cross-pieces ato a bearing ring 10. A discharge funnel 11 for the liquid overflowingat 8 is secured to the partition 6 By movement of the bearing ring It)by means of a block 13 engaging its annular groove 12 in the axialdirection of the centrifuge, the flow cross section of the annular gapbottom discharge 7 7 7 can be adjusted.

The shaft 2 is adapted to be driven by means not shown, so that thesolid-surface drum 1 with the bearing ring it) and the partitions 6 6 6rotate about the axis of the centrifuge.

The suspension to be separated into liquid and solid passes through thefeed pipe 5 into the first separating chamber 4 and forms a ring,rotating with the solidsurface drum 1, in which the heavier solidparticles travel outwardly, impinge on the inner surface of the flaringdrum 1 and slide on the latter toward the bottom discharge 7 The lighterliquid and the solid particles suspended in it and not yet depositedflow over the overflow 8 into the second separating chamber 4 in whichfurther solid particles are projected toward the inner surface of thedrum 1. The material passing through the overflow 8 into the thirdseparating chamber 43 still contains solid matter in small quantity andin the form of very fine particles, which again are separated againstthe inner surface of the drum 1. The liquid, clarified in three stagesin the drum 1, leaves practically clear, that is to say, withoutdisturbing traces of solid, via the discharge funnel II and is collectedin the discharge housing 14.

The solid particles separated in the separating chamber 4 slide alongthe inner surface of the drum 1 through the bottom discharges 7 7 7 tothe wide end of the flaring drum 1 and are discharged into asolid-matter collecting housing 15. The flow of solid over the innersurface of the flaring drum 1 is regulated by adjustment of the passagecross section of the bottom discharges 7 '7 7 so as to maintain acontinuous stream of solid matter and so that the latter always fillsthe passage cross section of the bottom discharges, thus preventing thepassage of free liquid through the bottom discharges.

On starting up the centrifuge, the bottom discharges '7 7 7 areadvantageously first closed entirely until a sufficiently large amountof solid matter has collected in front of them.

Instead of adjusting all three bottom discharges 7 7 7 that is to say,all three partitions 6 6 6 by means of a single bearing ring 10, eachpartition may be provided with its own bearing ring. For example, thepartitions 6 and 6 may be slidable axially on the support and each ofthese partitions may be connected by a ring of cross pieces 9 and 9extending along generatrices of the support 9 with each of two furtherbearing rings 10 and 10 mounted on the shaft. See the bearing rings 1010 and 10 illustrated in FIG. 1a. The cross pieces 9 of the partition 6pass to the bearing ring 10 through recesses in the partition 6 andrecesses in the bearing ring and the cross pieces 9 of partition 6 passto the bearing ring 10 of partition 6 through recesses in the bearingring 10 Like the cross pieces of the support 9, the cross pieces 9 and 9of the partitions 6 and 6 would also pass through recesses in the hubdisc of the solid-surface drum 1.

Adjustment of the partitions may be effected in accordance with theweight of the amount of solid matter situated in the separatingchambers, the bearing rings being drawn by a spring into the positioncorresponding to the closure position of the partitions. If the amountof solid matter then increases the pressure on the partition alsoincreases and the spring is tensioned, whereby the passage cross sectionof the bottom discharge is increased.

In the adjustment in common of the three bottom discharges 7 7 7 asshown in FIG. 1, adjustment of the bearing ring 10 may also be effectedin accordance with the quantity of solid matter discharged at the end ofthe solid-surface drum 1.

A vibration may be superimposed on the adjusting movement of the bearingring 10 for preventing bridge formation of solid particles at the bottomdischarge.

In the clarifying centrifuge shown in FIG. 2, there is connected to theflaring solid-surface drum 201, having two separating chambers 204 and204 a solid-surface drum 216, which is conical in the opposite sense ofthe drum 201. In the drum 216 there is provided a conveyor worm 217making a relative movement with regard to the drum 216. Said worm isconnected externally to a solid-surface drum 218, arrangedconcentrically to the solid-surface drum 216 and mounted by means of ahollow shaft 219 in the centrifuge housing. The shaft 202 of the drum201 and the hollow shaft 219 are adapted to be driven by means notshown.

Passing through the hollow shaft 219 is the feed pipe 205, fast with thecentrifuge housing, for the suspension to be separated, as well as adischarge pipe 220 for the clarified liquid, which discharge pipesurrounds the feed pipe with spacing, and which is also fast with thecentrifuge housing, and has a hollow disc-shaped liquid takeoff device221 at its end extending into the drum 201.

The solid matter issuing at the end of the drum 201 from the separatingchamber 204 comes within reach of the conveyor worm 217, and isdischarged by the latter through the free narrower opening of the drum216 and is collected in a chamber 222. The clarified liquid running overthe overflow 208 of the partition 206 leaves the centrifuge via theliquid take-off device 221, and the discharge path, confined by theannular space between feed pipe 205 and discharge pipe 220. The wall ofthe drum 218 may also serve as partition between solid and clarifiedliquid.

The shaft 202 carries a distributor head 223, rotating with, it for theuniform introduction of the suspension into the first separating chamber204 In the clarifying centrifuge shown in FIG. 3 the throughputdirection of the liquid in the separating chamher 304 is opposite to thethroughput of the solid. As in the centrifuge according to FIGS. 1 and2, the solid flows along the flaring solid-surface drum 301 and ispushed out by a conveyor worm 317 along the conical solidsurface drum316.

The suspension to be separated into liquid and solid, however, is fed tothe drum 301 through the feed pipe 305 at its wider end. The spacelimited outwardly by the abutting ends of the solid-surface drums 301and 316 forms the first separating chamber, from which the liquid phasepasses through the overflow 308 of partition 306 into the secondseparating chamber 304 and then through the overflow 308 of thepartition 306 into the separating chamber 304 now counted as thirdseparating chamber. The separating chamber 304 has an overflow 308,which is situated in the hub disc of the drum 301 4 and through whichthe clarified liquid is discharged into a discharge housing 324.

The shaft of the drum 301 is formed as a hollow shaft 325, and the drum316 also has a hollow shaft 326, the centrifuge drum consisting of thedrums 301 and 316 being journalled in the centrifuge housing by means ofthe hollow shafts 325 and 326. Journalled in the two hollow shafts 325and 326 is a shaft 327 carrying the conveyor worm 317, said shaft 327having a central bore 328 for the feed pipe 305 and orifices 329 for theexit of the fed suspension into the first separating chamber. The hollowshaft 325 and the shaft 327 are adapted to be driven at different speedsby means, not shown.

The partition 406 shown in FIG. 4 has an additional Wall formed by anannular projection 430 for deflecting the overflowing liquid phasetoward the drum 401. This additional wall is located opposite theoverflow 408 and deflects outwardly the stream of liquid issuing fromthe opening of the overflow 408, whereupon the stream flows inwardlyagain around the outer edge of the additional wall 430. Such anadditional wall, however, may also be provided in front in thethroughput direction of the liquid. The gap between the inner surface ofthe drum 401 and the additional wall 430 must be larger than thethickness of the layer of solid matter situated on the drum 401 in theregion of the gap.

In the embodiment shown in FIG. 5, a scraper centrifuge is connected infront of the flaring drum 501. This scraper centrifuge has asubstantially cylindrical solid-surface drum or annular shell 531, whichforms a pre-separation chamber and is journalled in the centrifugehousing by means of a hub disc 532 and a shaft 533. This cylindricalsolid-surface drum 531 carries on its end opposite the hub disc 532 theflaring solid-surface drum 501. The partitions 506 and 506 of the drum501 are connected together by cross pieces 534, and to the bearing ring510 via the discharge hopper 511 by means of a disc 535, cross pieces536 and a disc 537. These parts 535, 536, 537 are located outside thetwo drums 501 and 531.

The suspension fed through the supply pipe 505 passes through a verticalduct 538 into the drum 531, the bulk of the solid matter being depositedon the inner surface of this drum. The liquid, still containingparticles of solid matter, however, leaves the drum 531 via an overflow539 directed toward chamber 504 at the narrower end of the flaring drum501 and is completely clarified in the tWo successive separatingchambers 504 and 504 of drum 501.

The solid matter collecting in the solid-surface drum 531 isperiodically dischargetd in known manner by means of a scraping device540, while the solid matter sliding on the inner surface of thesolid-surface drum 501, regulated by the bottom discharges 507 and 507and continuously being discharged, enters the solid-matter collectinghousing 515.

The angle of flare of the wall of the drum is adapted to the angle ofrepose of the solid matter deposited in each case, and in theconstructional examples, it increases from the first separating chamberto the second separating chamber in the discharge direction of the solidmatter.

What is claimed is:

1. A centrifuge rotor for separating a suspension into liquid and solidcomprising a shaft; a flaring solid surface drum mounted on said shaftcoaxially therewith; at least two annular partitions arranged withinsaid drum coaxially therewith; said partitions forming consecutiveseparating chambers for the suspension within said drum; each of saidpartitions leaving between its outer boundary and the drum a gap for thedischarge of deposited solid along the inner drum surface toward thewider end of the drum and having an overflow for the liquid at a pointsituated closer to the drum axis than said discharge gap; means forsupplying the suspension to the separating chamber situated nearest tothe other end of said drum; and means for dischargclarified liquid fromthe separating chamber situated nearest to the ot her end of said drum;and means for discharging the deposited solid from the wider end of theflaring drum.

2. The combination defined in claim 1 in which at least one of saidpartitions is mounted axially shiftable in relation to the flaring drum,so as to allow the width of said discharge gap to be varied.

3. The combination defined in claim 2 in which at least two partitionsare separately shiftable in the axial direction.

4. The combination in claim 1 in which the angle of flare of the drumincreases in the solid discharge direction.

5. The combination defined in claim 1 in which the means for supplyingthe suspension are arranged to introduce the suspension into theseparation chamber situated nearest to the narrower end of the drum.

6. The combination defined in claim 1 in which the means for supplyingthe suspension are arranged to introduce the suspension into theseparation chamber situated nearest to the wider end of the drum.

7. The combination defined in claim 1 in Which the means for dischargingthe deposited solid from the drum comprise a further flaring solidsurface drum adjoining with its wider end the wider end of the firstnamed drum;

and a conveyor worm arranged in said further drum so as to be rotatablein relation to said drum and to engage the solid matter issuing fromsaid first named drum and to discharge it at the narrower end of saidfurther drum.

8. The combination defined in claim 5 in which the means for supplyingthe suspension comprise an annular shell connected to the narrower endof the flaring drum, formed as a pre-separation chamber for receivingthe suspension and having an overflow toward the narrower end of theflaring drum; scraper means being provided for the discharge of thesolid matter deposited in said pre-separation chamber.

9. The combination defined in claim 1 in which at least one of saidpartitions is provided with an annular projection formed to direct theoverflowing liquid outwardly toward the flaring drum.

M. CARY NELSON, Primary Examiner. H. T. KLINKSIEK, Assistant Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.3,322,336 May 30, 1967 Wilhelm Lohse et a1 rs in the above numbered pat-It is hereby certified that error appea Letters Patent should read asent requiring correction and that the said corrected below.

Column 4, line 74, strike ou and meansfor discharg-" and insert insteand for the discharge of the t "the other end of said d one drum; end ofthe drum a Signed and sealed this 14th day of November 1967.

(SEAL) Attest:

Edward M. Fletcher, Jr. EDWARD J. BRENNER Commissioner of PatentsAttesting Officer

1. A CENTRIFUGE ROTOR FOR SEPARATING A SUSPENSION INTO LIQUID AND SOLIDCOMPRISING A SHAFT; A FLARING SOLID SURFACE DRUM MOUNTED ON SAID SHAFTCOAXIALLY THEREWITH; AT LEAST TWO ANNULAR PARTITIONS ARRANGED WITHINSAID DRUM COAXIALLY THEREWITH; SAID PARTITIONS FORMING CONSECUTIVESEPARATING CHAMBERS FOR THE SUSPENSION WITHIN SAID DRUM; EACH OF SAIDPARTITIONS LEAVING BETWEEN ITS OUTER BOUNDARY AND THE DRUM A GAP FOR THEDISCHARGED OF DEPOSITED SOLID ALONG THE INNER DRUM SURFACE TOWARD THEWIDER END OF THE DRUM AND HAVING AN OVERFLOW FOR THE LIQUID AT A POINTSITUATED CLOSER TO THE DRUM AXIS THAN SAID DISCHARGE GAP; MEANS FORSUPPLYING THE SUSPENSION TO THE SEPARATING CHAMBER SITUATED NEAREST TOTHE OTHER END OF SAID DRUM; AND MEANS FOR DISCHARGCLARIFIED LIQUID FROMTHE SEPARATING CHAMBER SITUATED NEAREST TO THE OTHER END OF SAID DRUM;AND MEANS FOR DISCHARGING THE DEPOSITED SOLID FROM THE WIDER END OF THEFLARING DRUM.